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Chiral kagome superconductivity modulations with residual Fermi arcs
Hanbin Deng1, Hailang Qin2, Guowei Liu1
1Department of Physics, Southern University of Science and Technology, Shenzhen, China.
Nature
|August 21, 2024
Summary
Researchers discovered chiral kagome superconductivity in KV3Sb5 and CsV3Sb5, revealing a chiral pair density wave (PDW) with residual Fermi arcs. This finding demonstrates time-reversal symmetry breaking and orbital selectivity in superconductivity.
Area of Science:
- Condensed Matter Physics
- Superconductivity Research
- Materials Science
Background:
- Superconductivity with finite-momentum pairing can induce complex phenomena like spatial-gap modulations and Bogoliubov Fermi states.
- Experimental verification of the interplay between these phenomena has remained a significant challenge.
- Kagome metals like KV3Sb5 and CsV3Sb5 are platforms for exploring novel superconducting states.
Purpose of the Study:
- To experimentally detect and characterize chiral superconductivity modulations and residual Fermi arcs in KV3Sb5 and CsV3Sb5.
- To elucidate the relationship between spatial-gap modulations, pair-density modulations, and Bogoliubov Fermi states.
- To investigate the nature of the observed superconducting state, including its symmetry and orbital character.
Main Methods:
- Utilized normal and Josephson scanning tunneling microscopy at ultra-low temperatures (30 mK) with microelectronvolt energy resolution.
- Employed quasiparticle interference imaging to probe the electronic structure of in-gap states.
- Differentiated observed pair-density wave (PDW) order from impurity-induced effects.
Main Results:
- Observed a U-shaped superconducting gap with residual in-gap states exhibiting a chiral 2a × 2a spatial modulation.
- Detected magnetic-field-tunable chirality in the superconducting gap, consistent with chiral pair-density modulations.
- Identified segmented residual Fermi arcs, linked to reconstructed vanadium d-orbital states, serving as candidate Bogoliubov Fermi states.
Conclusions:
- Demonstrated the existence of a chiral pair density wave (PDW) state in KV3Sb5 and CsV3Sb5 that breaks time-reversal symmetry.
- Established a direct link between the chiral PDW and residual Fermi arcs, explaining them as partially suppressed d-orbital states.
- Uncovered orbital selectivity in the chiral PDW and confirmed the space-momentum correspondence in finite-momentum-paired superconductivity.
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